High capacity electrodes

ABSTRACT

An electrode comprises carbon nanoparticles and at least one of metal particles, metal oxide particles, metalloid particles and/or metalloid oxide particles. A surfactant attaches the carbon nanoparticles and the metal particles, metal oxide particles, metalloid particles and/or metalloid oxide particles to form an electrode composition. A binder binds the electrode composition such that it can be formed into a film or membrane. The electrode has a specific capacity of at least 450 mAh/g of active material when cycled at a charge/discharge rate of about 0.1 C.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. Ser. No.15/492,153, filed Apr. 20, 2017, which is a Continuation application ofU.S. Ser. No. 14/696,435, filed Apr. 25, 2015, now U.S. Pat. No.9,666,861, issued May 30, 2017, which is related to and claims prioritybenefits from U.S. provisional patent application Ser. No. 61/984,118filed on Apr. 25, 2014, and from U.S. provisional patent applicationSer. No. 62/094,709 filed on Dec. 19, 2014.

FIELD OF THE INVENTION

The present invention relates to electrochemical compositions andmethods of preparing those compositions. The compositions being anon-aggregating, preferably homogenous, integration of carbonnanomaterials with metal oxides, metal, metalloid, and/or metalloidoxide particles for use as high performance electrodes.

BACKGROUND OF THE INVENTION

Lithium-ion batteries are currently the most popular rechargeablebatteries due to their high energy densities, relatively high cellvoltages, and low weight-to-volume ratios. However, the voltage, chargecapacity, battery life, and rechargeability of lithium-ion batterieshave increased by relatively small increments over the past decade.

One issue in developing new battery technology is choosing suitableelectrode composition(s). Electrochemically active metal oxides such asFe₂O₃, Mn₂O₃ and CO₂O₃, graphite and silicon (Si), have long beeninvestigated for use as anode materials for lithium-ion batteriesbecause of their high theoretical capacities. Silicon, as well as manymetal oxides typically exhibits a significant irreversible capacity lossin its first cycle and rapid capacity fade during cycling. A cyclerefers to one charge and one discharge. Existing commercial anodes oftenhave a specific capacity of between about 300 and 400 mAh/g when cycledat a charge/discharge rate of about 0.1 C and often suffer fromirreversible loss. Thus, it has been difficult to achieve a specificcapacity of more than about 400 mAh/g when cycled at a charge/dischargerate of about 0.1 C or higher over multiple charge/discharge cycles.

Furthermore, a large specific volume change commonly occurs during thecycling processes, which can lead to pulverization of the electrodes andrapid capacity decay. Furthermore swelling and contraction of siliconcan affect the structure and properties of the electrodes.

It has been thought that the application of nanomaterials, particularlynanotubes, in batteries can offer vast improvements. Nanoparticles caninclude submicron (usually less than 1000 nm) carbon materials and/ornanoscale (usually less than 100 nm) carbon materials. The nanoparticlespreferably have at least one dimension that is less than 500 nm, morepreferably less than 100 nm and sometimes no greater than about 1 nm.Nanoparticles include, for example, nanospheres, nanorods, nanocups,nanowires, nanoclusters, nanofibers, nanolayers, nanotubes,nanocrystals, nanobeads, nanobelts and nanodisks.

Nanotubes are cylindrical structures formed by nanoparticles such ascarbon-based nanoparticles. Nanotubes can be single-walled nanotubes(“SWNT”), multi-walled nanotubes (“MWNT”) which includes double-wallednanotubes (“DWNT”), or a combination of the same. When the nanotube iscarbon-based the abbreviation can be modified by a “C-,” for example,C-SWNT and C-MWNT.

The structure of a single-walled carbon nanotube can be described as asingle graphene sheet rolled into a seamless cylinder with ends that areeither open, or capped by either half fullerenes or more complexstructures such as pentagons. Multi-walled carbon nanotubes contain twoor more nanotubes that are concentrically nested, like rings of a treetrunk, with a typical distance of about 0.34 nm between layers.

Nanomaterials have broad industrial applications, including transparentelectrodes for displays and solar cells, electromagnetic interferenceshielding, and sensors. Nanoparticles, and specifically conductivenanoparticles of carbon, metals and the like, have been known and usedfor years in the fields of semiconductors and electronic devices.Examples of such particles and processes are provided in U.S. Pat. Nos.7,078,276; 7,033,416; 6,878,184; 6,833,019; 6,585,796; 6,572,673; and6,372,077. The advantages of having ordered nanoparticles in theseapplications are also well established (see, for example, U.S. Pat. No.7,790,560).

Nanoparticles of various materials have been selected for a range ofapplications based on their various thermal and electrical conductivityproperties. Among the nanoparticles often used are carbon nanoparticles:nanoparticles that are primarily composed of carbon atoms, includingdiamond, graphite, graphene, fullerenes, carbon nanotubes (includingC-SWNT and C-MWNT), carbon nanotube fiber (carbon nanotube yarn), carbonfibers, and combinations thereof, which are not magnetically sensitive.Carbon nanoparticles include those particles with structural defects andvariations, tube arrangements, chemical modification andfunctionalization, surface treatment, and encapsulation.

In particular, carbon nanotubes are very promising due to their chemicalstability combined with electrical and thermal conductivity. Carbonnanotubes are long thin cylindrical macromolecules and thus have a highaspect ratio (ratio of the length over the diameter of a particle).

Nanoparticles, and in particular nanotubes, can enhance the strength,elasticity, toughness, electrical conductivity and thermal conductivityof various compositions. In certain applications the use of carbonnanotubes in materials is desirable yet hard to achieve. For example,nanotubes have a tendency to aggregate (also referred to as bundle oragglomerate), which impairs their dispersion. Non-uniform dispersion cangive rise to a variety of problems, including reduced and inconsistenttensile strength, elasticity, toughness, electrical conductivity, andthermal conductivity. Generally, preparation of most materialsincorporating single-walled carbon nanotubes and/or multi-walled carbonnanotubes has been directed at achieving well-dispersed nanotubes inpolymers using methods such as mechanical mixing, melt-blending, solventblending, in-situ polymerization, and combinations of the same. Attemptsto create homogenous aqueous dispersions of single-walled andmulti-walled carbon nanotubes have involved using certain water-solublepolymers that interact with the nanotubes to give the nanotubessolubility in aqueous systems such as the systems described inInternational (PCT) Publication No. WO 02/016257. However, theseattempts have not been able to reach the desired dispersion due tomultiple factors. Nanoparticles, particularly multi-walled,double-walled and single-walled carbon nanotubes, have a tendency toaggregate, which leads to non-uniform dispersion. Furthermorenanoparticles, and in particular nanotubes, often have relativelyfragile structures that are damaged by many of the existing physicaldispersion methods, such as mixing and intense or extendedultrasonication. In addition, it is believed that the geometrical shapeof many nanoparticles and intramolecular forces contribute to a tendencyfor less uniform dispersion.

Previous attempts have been made to disperse nanoparticles and metaloxides in fluids (see, for example, U.S. Patent Application PublicationNo. US2008/0302998). However, these attempts did not address the properdispersion of carbon nanomaterials and metal oxides and/or metalparticles for desirable electrical conductivity and the formation ofsolid electrodes. Similarly, although U.S. Pat. No. 8,652,386 describesmagnetic alignment of carbon nanotubes in nanofluids such as nanogreasesand nanolubricants by employing metal oxides in the fluids, the priorart has been silent on the successful homogenous dispersion andintegration of carbon nanomaterials with metal oxides and/or metaland/or metalloid particles in useful materials such as electrodes.Integration refers to when the ion absorbing particles are combined inan integrated fashion so that they are attached to the carbonnanoparticles.

U.S. Patent Application Publication No. US 2013/0224603 discusseselectrodes comprising a mesa-porous graphene cathode and an anodecomprising an active material for inserting and extracting lithium mixedwith a conductive filler and/or resin binder. However, the methodsdisclosed have several limitations including construction of the anodein a conventional manner involving simple mixing of the components, anddoes not include any method of providing uniform dispersion of theactive material or robust attachment of the active material to theconductive filler.

Similarly U.S. Pat. No. 8,580,432 discusses a composition forlithium-ion battery electrode applications comprising a lithium-ionconductive material in the form of submicron particles, rods, wires,fibers or tubes combined with nano-graphene platelets and incorporatedin a protective matrix material. However, the patent does not disclose amethod of ensuring uniform dispersion of the components or homogeneousdistribution of the submicron additives and nano-graphene platelets inthe matrix material.

Attempts to disperse carbon nanoparticles have included the use ofnanotubes functionalized with magnetically sensitive groups includingNi-coated nanotubes. However, this approach failed as the functionalizednanotubes were found to suffer a decrease in electrical conductivity,strength and other mechanical properties in part due to the fact thatonce functionalized, the conjugated structure of the nanotubes isbroken, which results in changes in surface properties.

Thus, it remains a serious technical challenge to effectively andefficiently disperse carbon nanotubes into a non-aggregating, preferablyhomogenous and uniform, integration with metal oxides and/or metalparticles and/or silicon and/or silicon oxides, thereby providingmaterials having consistent electrical conductivity properties and/orimproved capacitance for high performance energy storage systems.

There is a need for novel methods to develop essentially homogenous anduniform integration of electrically conducting carbon nanoparticles suchas nanotubes and graphene for high performance electrodes in such a waythat the integrity and functionality of the electrode is not affected byvolume changes in the ion-absorbing component. This would potentiallysignificantly enhance the capacity, performance, and lifetime of energystorage systems. In one of the embodiments described below, carbonnanoparticles are integrated with at least one of metals, metal oxides,silicon and/or silicon oxides for use as electrodes.

BRIEF SUMMARY OF THE INVENTION

The present electrodes comprise carbon nanoparticles, at least one ofmetal, metal oxide, metalloid, and/or metalloid oxide particles, asurfactant for attaching the carbon nanoparticles to at least one ofmetal, metal oxide, metalloid, and/or metalloid oxide particles to forman electrode composition, and a binder to form the electrode compositioninto a film. The electrodes can have a specific capacity of at least 450mAh/g of active material when cycled at a charge/discharge rate of about0.1 C.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a scanning electron microscope (SEM) image of iron oxide(Fe₂O₃) nanoparticles dispersed and attached on the carbon nanofiberswithout substantial aggregation. The surfactant used was sodiumdodecylbenzene sulfonate.

FIG. 2 shows an SEM image of silicon (Si) nanoparticles dispersed andattached on the carbon nanofibers without substantial aggregation. Thesurfactant used was cetyltrimethylammonium bromide.

FIG. 3 shows an SEM image of silicon (Si) nanoparticles dispersed andattached on the single wall carbon nanotubes (C-SWNT) withoutsubstantial aggregation. The surfactant used was cetyltrimethylammoniumbromide.

FIG. 4 shows an SEM image of silicon (Si) nanoparticles dispersed andattached on the single wall carbon nanotubes (C-SWNT) withoutsubstantial aggregation. The surfactant used was benzethonium chloride.

FIG. 5 shows a transmission electron microscopy (TEM) image of ironoxide (Fe₂O₃) nanoparticles dispersed and attached on the graphenewithout substantial aggregation. The surfactant used was sodiumdodecylbenzenesulfonate.

FIG. 6 shows a TEM image of silicon (Si) nanoparticles dispersed andattached on the graphene without substantial aggregation. The surfactantused was benzethonium chloride.

FIG. 7 is a cross-sectional diagram of a thin film lithium-ion batterywherein the anode and/or the cathode have an electrode composition asdescribed herein.

FIG. 8 is a graph showing the specific capacity measured from thedischarge cycle (per unit mass of active material) over multiple(charge/discharge) cycles for an electrode in which surfactant was notincluded in the formulation, and which comprises Fe₂O₃ nanoparticlesmixed with graphene nanoparticles as the active materials.

FIG. 9 is a graph showing the specific capacity measured from thedischarge cycle (per unit mass of active material) over 94(charge/discharge) cycles for an anode material in which sodiumdodecylbenzenesulfonate surfactant was used in the material preparation,and which comprises Fe₂O₃ nanoparticles combined with graphenenanoparticles as the active materials.

FIG. 10 is a graph showing specific capacity measured from the dischargecycle (per unit mass of active material) over 23 (charge/discharge)cycles for an anode material in which benzyldodecyldimethylammoniumbromide surfactant was used in the material preparation, and whichcomprises silicon nanoparticles combined with carbon nanotubes as theactive materials.

FIG. 11 is a flow diagram illustrating an example method of forming anelectrode for an electrochemical battery cell.

DETAILED DESCRIPTION OF EMBODIMENT(S)

The present electrode compositions have high capacity and highperformance in energy storage systems. The presently disclosed electrodecompositions comprise carbon nanoparticles or nanotubes attached tometal oxides, metal particles, metalloid particles and/or metalloidoxides in a non-aggregating, preferably homogeneous and uniform,dispersion.

The ranges recited are meant to identify all integers and fractionsencompassed within the ranges.

Electrode Compositions

Non-aggregating, preferably homogenously dispersed, carbon nanomaterialssuch as carbon nanotubes with metal oxides, metal, metalloid, and/ormetalloid oxide particles provide various benefits over other materialsfor use in electrodes. It is believed that the non-aggregationdispersion of nanoparticles improves the flow of ions or electrons andprovides a more ordered structure which enhances various mechanical andelectrical properties. This can result in improved structural propertiesof the material as a whole and thus improved physical properties,including, but not limited to, electrical conductivity, thermalconductivity, increased tensile modulus (stiffness), flexural modulus,tensile strength, flexural strength, elasticity, and toughness.Moreover, the dispersion and integration prevents or at least reducesthe aggregation among the nanoparticles and leads to enhanced physicalcharacteristics of the attached constituents.

The components in the present electrode compositions can be selectedbased upon their stability, solubility, thermophysical, electrical,mechanical, size, and zeta potential (for example, surface charge)properties.

Particular pH values can facilitate the dispersion of the nanoparticlesand attaching the carbon nanoparticles to metal oxides and/or metalparticles, and combinations of the same. In one embodiment, if thesurfactant(s) have a net negative charge, the pH of the nanoparticlefluid is greater than about 5. In another embodiment, if thesurfactant(s) have a net positive charge, the pH of thenanoparticle/host material mixture in solvent is less than about 10.

Carbon Nanoparticles

Carbon nanoparticles are included in the present electrode compositions.Carbon nanoparticles have high electrical conductivity, which oftenexceeds that of metallic materials. Carbon nanoparticles are inclusiveof nanoparticles, including submicron nanofibers. Many forms of carbonnanoparticles are suitable for use in the present compositions,including activated carbon nanoparticles, porous carbon nanoparticles,carbon nanotubes, fullerenes, graphite, graphene, nanofibers, andcombinations thereof.

Carbon nanotubes (CNTs), have a high heat transfer coefficient and highthermal conductivity, which often exceeds those of metallic materials.For example, C-SWNTs can exhibit a thermal conductivity value as high as2000-6000 W/m-K under ideal circumstances. Many forms of CNTs can beused in the present compositions, including C-SWNTs, C-MWNTs, hollowcarbon nanofibers, and combinations thereof.

In many nanotubes, particularly CNTs, the basic structural element is ahexagon, which is the same as that found in graphite. Based on theorientation of the tube axis with respect to the hexagonal lattice, ananotube can have three different configurations: armchair, zigzag, andchiral (also known as spiral). In an armchair configuration, the tubeaxis is perpendicular to two of six carbon-carbon bonds of the hexagonallattice. In a zigzag configuration, the tube axis is parallel to two ofsix carbon-carbon bonds of the hexagonal lattice. Both of theseconfigurations are achiral. In a chiral configuration, the tube axisforms an angle other than 90 or 180 degrees with one of the sixcarbon-carbon bonds of the hexagonal lattice. Nanotubes of theseconfigurations often exhibit different physical and chemical properties.For example, an armchair nanotube is usually metallic whereas a zigzagnanotube can be metallic or semi conductive depending on the diameter ofthe nanotube. All three different configurations are expected to be verygood thermal conductors along the tube axis, exhibiting a property knownas “ballistic conduction,” but good insulators laterally to the tubeaxis.

In addition to the common hexagonal structure, the cylinder of nanotubemolecules can also contain other size rings, such as pentagon, heptagon,and octagon. Replacement of some regular hexagons with other ringstructures, such as pentagons and/or heptagons, can cause cylinders tobend, twist, or change diameter, and thus lead to some interestingstructures such as Y-, T-, and X-junctions, and different chemicalactivities. Those various structural variations and configurations canbe found in both SWNT and MWNT.

Nanotubes used in the present electrode compositions can be in theconfiguration of armchair, zigzag, chiral, or combinations thereof. Thenanotubes can also contain structural elements other than hexagon, suchas pentagon, heptagon, octagon, or combinations thereof.

Another structural variation for MWNT molecules is the arrangement ofmultiple nanotubes. An exemplary C-MWNT is like a stack of graphenesheets rolled up into concentric cylinders with each wall parallel to acentral axis. However, the tubes can also be arranged so that an anglebetween the graphite basal planes and the tube axis is formed. SuchMWNT, whether carbon-based or not, is known as a stacked cone, chevron,bamboo, ice cream cone, or piled cone structures. A stacked cone MWNTcan reach a diameter of about 100 μm. In spite of these structuralvariations, many types of MWNTs are suitable for use in the presentcompositions.

The nanotubes that are used can also encapsulate other elements and/ormolecules within their enclosed tubular structures. Such elementsinclude Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Mo, Ta, Au, Th, La,Ce, Pr, Nb, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Mo, Pd, Sn, and W. Suchmolecules include alloys of these elements such as alloys of cobalt withS, Br, Ph, Pt, Y, Cu, B, and Mg, and compounds such as carbides such asTiC and MoC. The presence of these elements, alloys and compounds withinthe core structure of the nanotubes can enhance the various properties,such as thermal and/or electrical conductivity.

Nanotubes are commercially available from a variety of sources. Manypublications are available with sufficient information to allow one tomanufacture nanotubes with desired structures and properties. Commontechniques are arc discharge, laser ablation, chemical vapor deposition,and flame synthesis. Chemical vapor deposition has shown great promisein being able to produce larger quantities of nanotubes at lower cost.This is usually done by reacting a carbon-containing gas, such asacetylene, ethylene or ethanol, with a metal catalyst particle, such ascobalt, nickel, or ion, at temperatures above 600° C.

The selection of a particular nanotube depends on a number of factors.Factors include desired physical properties, such as electrical andthermal conductivity, mass, and tensile strength; cost effectiveness;solubility; and dispersion and settling characteristics. In someembodiments of the present materials, the nanotubes selected comprise,consist of, or consist essentially of CNTs. In other embodiments or thesame embodiments, the nanotubes comprise, consist of, or consistessentially of SWNTs. In other embodiments, the nanotubes comprise,consist of, or consist essentially of multi-walled nanotubes (MWNTs). Inyet other embodiments, the nanotubes comprise, consist of, or consistessentially of CNTs that are functionalized chemically.

In other embodiments, the carbon nanoparticles are single, bilayer ormultilayer graphene. In yet other embodiments, the carbon nanoparticlescan be single, bilayer or multilayer graphene oxide or otherfunctionalized graphene.

In some embodiments the present compositions comprise between about 5wt. % and 95 wt. % carbon nanoparticles. In some embodiments the presentcompositions comprise between about 10 wt. % and 75 wt. % carbonnanoparticles. In some embodiments the present compositions comprisebetween about 15 wt. % and 50 wt. % carbon nanoparticles.

Metal Oxide Particles

The present electrode compositions can further comprise metal oxideparticles. In certain embodiments the metal oxide particles arenanoparticles. A metal oxide nanoparticle is a nanoscale particle thatcomprises one or more metal oxides. Suitable metal oxides include butare not limited to Al₂O₃, CuO, MgO, V₂O₅, BiO₂, Sb₂O₅, TiO₂, ZnO, Fe₂O₃,Fe₃O₄, CrO₃, NiO, Ni₂O₃, CoO, CO₂O₃, and CO₃O₄. Furthermore, unlessspecified, the chemical formula of a nanoparticle represents any of thepossible crystalline forms and/or, where applicable, an amorphous form.For example, the chemical formula Al₂O₃ can represent alpha-, beta-, orgamma-aluminum oxide, or combinations thereof.

In some embodiments of the present compositions the metal oxideparticles have a pH point of zero charge (pHpzc) of between 6 and 10, 7and 10, 8 and 10, and 9 and 10, for example. Exemplary metal oxides,MgO, CuO, Al₂O₃, Fe₂O₃ and Fe₃O₄, have a pHpzc between about 6 and about10. Silicon has a pHpzc between about 4 and about 5. “pHpzc” refers tothe pH value of a fluid containing the metal oxideparticles, metalparticles, metalloid particles, and/or metalloid oxide particles atwhich the metal oxide particles, metal particles, metalloid particles,and/or metalloid oxide particles exhibit a neutral surface charge.

In some embodiments of the present compositions metal oxides are betweenabout 5 wt. % and 95 wt. % of the composition. In some embodiments metaloxides are between about 10 wt. % and 90 wt. % of the composition. Insome embodiments metal oxides are between about 15 wt. % and 85 wt. % ofthe composition.

Metal Particles

The present electrode compositions can further comprise metal particles.In some embodiments the metal particles can be nanoparticles. Suitablemetal particles include, but are not limited to lanthanides (forexample, lanthanum, cerium, praseodymium, neodymium, promethium,samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium,thulium, ytterbium, and lutetium), cobalt, vanadium, manganese, niobium,iron, nickel, copper, titanium, zirconium, tin, other rare earth metalssuch as scandium and yttrium, and combinations and alloys of theaforementioned metals and/or metal oxides. In some embodiments of thepresent materials the metal particles, include, but are not limited to,NdFeB, Fe and Ni.

In some embodiments of the present electrode compositions metalparticles are between about 5 wt. % and 95 wt. % of the composition. Insome embodiments metal oxides are between about 10 wt. % and 90 wt. % ofthe composition. In some embodiments metal oxides are between about 15wt. % and 85 wt. % of the composition.

Metalloid Particles

The present electrode compositions can further comprise metalloidparticles. In some embodiments the metalloid particles can benanoparticles. Suitable metalloid particles include, but are not limitedto boron, silicon, germanium, tellurium, and oxides, combinations, andalloys of the aforementioned metalloids. Suitable metalloid oxidesinclude but are not limited to SiO₂, GeO₂, B₂O₃, and TeO₂ and/or, whereapplicable, amorphous forms. Furthermore, unless specified, the chemicalformula of a nanoparticle represents any of the possible crystallineforms. For example, the chemical formula B₂O₃ can represent alpha- orbeta-boron oxide, or combinations thereof.

In some embodiments of the present electrode compositions metalloidparticles are between about 5 wt. % and 95 wt. % of the composition. Insome embodiments metal oxides are between about 10 wt. % and 90 wt. % ofthe composition. In some embodiments metal oxides are between about 15wt. % and 85 wt. % of the composition.

Surfactants

Surfactants are molecules or groups of molecules having surfaceactivity, including wetting agents, dispersants, emulsifiers,detergents, and foaming agents. A variety of surfactants can be used inpreparation of the present materials as a dispersant to facilitateuniform dispersion of nanoparticles in the material, and/or to enhancestabilization of such a dispersion. Typically, the surfactants usedcontain a lipophilic nonpolar hydrocarbon group and a polar functionalhydrophilic group. The polar functional group can be a carboxylate,ester, amine, amide, imide, hydroxyl, ether, nitrile, phosphate,sulfate, or sulfonate. The surfactants can be used alone or incombination. Accordingly, a combination of surfactants can includeanionic, cationic, nonionic, zwitterionic, amphoteric, and ampholyticsurfactants, so long as there is a net positive or negative charge inthe head regions of the population of surfactant molecules. In manyinstances, a single negatively charged or positively charged surfactantis used in the preparation of the present electrode compositions.

Accordingly, a surfactant used in preparation of the present electrodecompositions can be anionic, including, but not limited to, sulfonatessuch as alkyl sulfonates, alkylbenzene sulfonates, alpha olefinsulfonates, paraffin sulfonates, and alkyl ester sulfonates; sulfatessuch as alkyl sulfates, alkyl alkoxy sulfates, and alkyl alkoxylatedsulfates; phosphates such as monoalkyl phosphates and dialkylphosphates; phosphonates; carboxylates such as fatty acids, alkyl alkoxycarboxylates, sarcosinates, isethionates, and taurates. Specificexamples of carboxylates are sodium oleate, sodium cocoyl isethionate,sodium methyl oleoyl taurate, sodium laureth carboxylate, sodiumtrideceth carboxylate, sodium lauryl sarcosinate, lauroyl sarcosine, andcocoyl sarcosinate. Specific examples of sulfates include sodium dodecylsulfate (SDS), sodium lauryl sulfate, sodium laureth sulfate, sodiumtrideceth sulfate, sodium tridecyl sulfate, sodium cocyl sulfate, andlauric monoglyceride sodium sulfate.

Suitable sulfonate surfactants include, but are not limited to, alkylsulfonates, aryl sulfonates, monoalkyl and dialkyl sulfosuccinates, andmonoalkyl and dialkyl sulfosuccinamates. Each alkyl group independentlycontains about two to twenty carbons and can also be ethoxylated with upto about 8 units, preferably up to about 6 units, on average, forexample, 2, 3, or 4 units, of ethylene oxide, per each alkyl group.Illustrative examples of alky and aryl sulfonates are sodium tridecylbenzene sulfonate (STBS) and sodium dodecylbenzene sulfonate (SDBS).

Illustrative examples of sulfosuccinates include, but are not limitedto, dimethicone copolyol sulfosuccinate, diamyl sulfosuccinate, dicaprylsulfosuccinate, dicyclohexyl sulfosuccinate, diheptyl sulfosuccinate,dihexyl sulfosuccinate, diisobutyl sulfosuccinate, dioctylsulfosuccinate, C12-15 pareth sulfosuccinate, cetearyl sulfosuccinate,cocopolyglucose sulfosuccinate, cocoyl butyl gluceth-10 sulfosuccinate,deceth-5 sulfosuccinate, deceth-6 sulfosuccinate, dihydroxyethylsulfosuccinylundecylenate, hydrogenated cottonseed glyceridesulfosuccinate, isodecyl sulfosuccinate, isostearyl sulfosuccinate,laneth-5 sulfosuccinate, laureth sulfosuccinate, laureth-12sulfosuccinate, laureth-6 sulfosuccinate, laureth-9 sulfosuccinate,lauryl sulfosuccinate, nonoxynol-10 sulfosuccinate, oleth-3sulfosuccinate, oleyl sulfosuccinate, PEG-10 laurylcitratesulfosuccinate, sitosereth-14 sulfosuccinate, stearyl sulfosuccinate,tallow, tridecyl sulfosuccinate, ditridecyl sulfosuccinate, bisglycolricinosulfosuccinate, di(1,3-di-methylbutyl)sulfosuccinate, and siliconecopolyol sulfosuccinates.

Illustrative examples of sulfosuccinamates include, but are not limitedto, lauramido-MEA sulfosuccinate, oleamido PEG-2 sulfosuccinate,cocamido MIPA-sulfosuccinate, cocamido PEG-3 sulfosuccinate,isostearamido MEA-sulfosuccinate, isostearamido MIPA-sulfosuccinate,lauramido MEA-sulfosuccinate, lauramido PEG-2 sulfosuccinate, lauramidoPEG-5 sulfosuccinate, myristamido MEA-sulfosuccinate, oleamidoMEA-sulfosuccinate, oleamido PIPA-sulfosuccinate, oleamido PEG-2sulfosuccinate, palmitamido PEG-2 sulfosuccinate, palmitoleamido PEG-2sulfosuccinate, PEG-4 cocamido MIPA-sulfosuccinate, ricinoleamidoMEA-sulfosuccinate, stearamido MEA-sulfosuccinate, stearylsulfosuccinamate, tallamido MEA-sulfosuccinate, tallow sulfosuccinamate,tallowamido MEA-sulfosuccinate, undecylenamido MEA-sulfosuccinate,undecylenamido PEG-2 sulfosuccinate, wheat germamido MEA-sulfosuccinate,and wheat germamido PEG-2 sulfosuccinate.

Some examples of commercial sulfonates are AEROSOL® OT-S, AEROSOL®OT-MSO, AEROSOL® TR70% (Cytec Inc., West Paterson, N.J.), NaSul CA-HT3(King Industries, Norwalk, Conn.), and C500 (Crompton Co., West Hill,Ontario, Canada). AEROSOL® OT-S is sodium dioctyl sulfosuccinate inpetroleum distillate. AEROSOL® OT-MSO also contains sodium dioctylsulfosuccinate. AEROSOL® TR70% is sodium bistridecyl sulfosuccinate inmixture of ethanol and water. NaSul CA-HT3 is calcium dinonylnaphthalenesulfonate/carboxylate complex. C500 is an oil soluble calcium sulfonate.

Alkyl or alkyl groups refers to saturated hydrocarbons having one ormore carbon atoms, including straight-chain alkyl groups (for example,methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl,decyl, and so on), cyclic alkyl groups (or cycloalkyl or alicyclic orcarbocyclic groups) (for example, cyclopropyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, and so on), branched-chain alkyl groups (forexample, isopropyl, tert-butyl, sec-butyl, isobutyl, and so on), andalkyl-substituted alkyl groups (for example, alkyl-substitutedcycloalkyl groups and cycloalkyl-substituted alkyl groups).

Alkyl can include both unsubstituted alkyls and substituted alkyls.Substituted alkyls refers to alkyl groups having substituents replacingone or more hydrogens on one or more carbons of the hydrocarbonbackbone. Such substituents can include, alkenyl, alkynyl, halogeno,hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxy,aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl,alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl,alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, cyano,amino (including alkyl amino, dialkylamino, arylamino, diarylamino andalkylarylamino), acylamino (including alkylcarbonylamino,arylcarbonylamino, carbamoyl and ureido), imino, sulfhydryl, alkylthio,arylthio, thiocarboxylate, sulfates, alkylsulfinyl, sulfonates,sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, azido,heterocyclic, alkylaryl or aromatic (including heteroaromatic) groups.

In some embodiments, substituted alkyls can include a heterocyclicgroup. Heterocyclic groups include closed ring structures analogous tocarbocyclic groups in which one or more of the carbon atoms in the ringis an element other than carbon, for example, nitrogen, sulfur oroxygen. Heterocyclic groups can be saturated or unsaturated. Exemplaryheterocyclic groups include, aziridine, ethylene oxide (epoxides,oxiranes), thiirane (episulfides), dioxirane, azetidine, oxetane,thietane, dioxetane, dithietane, dithiete, azolidine, pyrrolidine,pyrroline, oxolane, dihydrofuran and furan.

For an anionic surfactant, the counter ion is typically sodium but canalternatively be potassium, lithium, calcium, magnesium, ammonium,amines (primary, secondary, tertiary or quandary) or other organicbases. Exemplary amines include isopropylamine, ethanolamine,diethanolamine, and triethanolamine. Mixtures of the above cations canalso be used.

A surfactant used in preparation of the present materials can becationic. Such cationic surfactants include, but are not limited to,pyridinium-containing compounds, and primary, secondary tertiary orquaternary organic amines. For a cationic surfactant, the counter ioncan be, for example, chloride, bromide, methosulfate, ethosulfate,lactate, saccharinate, acetate and phosphate. Examples of cationicamines include polyethoxylated oleyl/stearyl amine, ethoxylated tallowamine, cocoalkylamine, oleylamine and tallow alkyl amine, as well asmixtures thereof.

Examples of quaternary amines with a single long alkyl group arecetyltrimethyl ammonium bromide (CTAB), benzyldodecyldimethylammoniumbromide (BddaBr), benzyldimethylhexadecylammonium chloride (BdhaCl),dodecyltrimethylammonium bromide, myristyl trimethyl ammonium bromide,stearyl dimethyl benzyl ammonium chloride, oleyl dimethyl benzylammonium chloride, lauryl trimethyl ammonium methosulfate (also known ascocotrimonium methosulfate), cetyl-dimethyl hydroxyethyl ammoniumdihydrogen phosphate, bassuamidopropylkonium chloride, cocotrimoniumchloride, distearyldimonium chloride, wheat germ-amidopropalkoniumchloride, stearyl octyidimonium methosulfate, isostearaminopropal-koniumchloride, dihydroxypropyl PEG-5 linoleammonium chloride, PEG-2stearmonium chloride, behentrimonium chloride, dicetyl dimoniumchloride, tallow trimonium chloride and behenamidopropyl ethyl dimoniumethosulfate.

Examples of quaternary amines with two long alkyl groups aredidodecyldimethylammonium bromide (DDAB), distearyldimonium chloride,dicetyl dimonium chloride, stearyl octyldimonium methosulfate,dihydrogenated palmoylethyl hydroxyethylmonium methosulfate,dipalmitoylethyl hydroxyethylmonium methosulfate, dioleoylethylhydroxyethylmonium methosulfate, and hydroxypropyl bisstearyldimoniumchloride.

Quaternary ammonium compounds of imidazoline derivatives include, forexample, isostearyl benzylimidonium chloride, cocoyl benzyl hydroxyethylimidazolinium chloride, cocoyl hydroxyethylimidazolinium PG-chloridephosphate, and stearyl hydroxyethylimidonium chloride. Otherheterocyclic quaternary ammonium compounds, such as dodecylpyridiniumchloride, amprolium hydrochloride (AH), and benzethonium hydrochloride(BH) can also be used.

A surfactant used in preparation of the present materials can benonionic, including, but not limited to, polyalkylene oxide carboxylicacid esters, fatty acid esters, fatty alcohols, ethoxylated fattyalcohols, poloxamers, alkanolamides, alkoxylated alkanolamides,polyethylene glycol monoalkyl ether, and alkyl polysaccharides.Polyalkylene oxide carboxylic acid esters have one or two carboxylicester moieties each with about 8 to 20 carbons and a polyalkylene oxidemoiety containing about 5 to 200 alkylene oxide units. An ethoxylatedfatty alcohol contains an ethylene oxide moiety containing about 5 to150 ethylene oxide units and a fatty alcohol moiety with about 6 toabout 30 carbons. The fatty alcohol moiety can be cyclic, straight, orbranched, and saturated or unsaturated. Some examples of ethoxylatedfatty alcohols include ethylene glycol ethers of oleth alcohol, stearethalcohol, lauryl alcohol and isocetyl alcohol. Poloxamers are ethyleneoxide and propylene oxide block copolymers, having from about 15 toabout 100 moles of ethylene oxide. Alkyl polysaccharide (“APS”)surfactants (for example, alkyl polyglycosides) contain a hydrophobicgroup with about 6 to about 30 carbons and a polysaccharide (forexample, polyglycoside) as the hydrophilic group. An example ofcommercial nonionic surfactant is FOA-5 (Octel Starreon LLC., Littleton,Colo.).

Specific examples of suitable nonionic surfactants include alkanolamidessuch as cocamide diethanolamide (“DEA”), cocamide monoethanolamide(“MEA”), cocamide monoisopropanolamide (“MIPA”), PEG-5 cocamide MEA,lauramide DEA, and lauramide MEA; alkyl amine oxides such as lauramineoxide, cocamine oxide, cocamidopropylamine oxide, andlauramidopropylamine oxide; sorbitan laurate, sorbitan distearate, fattyacids or fatty acid esters such as lauric acid, isostearic acid, andPEG-150 distearate; fatty alcohols or ethoxylated fatty alcohols such aslauryl alcohol, alkylpolyglucosides such as decyl glucoside, laurylglucoside, and coco glucoside.

A surfactant used in preparation of the present materials can bezwitterionic, having both a formal positive and negative charge on thesame molecule. The positive charge group can be quaternary ammonium,phosphonium, or sulfonium, whereas the negative charge group can becarboxylate, sulfonate, sulfate, phosphate or phosphonate. Similar toother classes of surfactants, the hydrophobic moiety can contain one ormore long, straight, cyclic, or branched, aliphatic chains of about 8 to18 carbon atoms. Specific examples of zwitterionic surfactants includealkyl betaines such as cocodimethyl carboxymethyl betaine, lauryldimethyl carboxymethyl betaine, lauryl dimethyl alpha-carboxyethylbetaine, cetyl dimethyl carboxymethyl betaine, laurylbis-(2-hydroxyethyl)carboxy methyl betaine, stearylbis-(2-hydroxypropyl)carboxymethyl betaine, oleyl dimethylgamma-carboxypropyl betaine, and laurylbis-(2-hydroxypropyl)alphacarboxy-ethyl betaine, amidopropyl betaines;and alkyl sultaines such as cocodimethyl sulfopropyl betaine,stearyidimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine,lauryl bis-(2-hydroxyethyl)sulfopropyl betaine, andalkylamidopropylhydroxy sultaines.

A surfactant used in preparation of the present materials can beamphoteric. Examples of suitable amphoteric surfactants include ammoniumor substituted ammonium salts of alkyl amphocarboxy glycinates and alkylamphocarboxypropionates, alkyl amphodipropionates, alkylamphodiacetates, alkyl amphoglycinates, and alkyl amphopropionates, aswell as alkyl iminopropionates, alkyl iminodipropionates, and alkylamphopropylsulfonates. Specific examples are cocoamphoacetate,cocoamphopropionate, cocoamphodiacetate, lauroamphoacetate,lauroamphodiacetate, lauroamphodipropionate, lauroamphodiacetate,cocoamphopropyl sulfonate, caproamphodiacetate, caproamphoacetate,caproamphodipropionate, and stearoamphoacetate.

A surfactant used in preparation of the present materials can also be apolymer such as N-substituted polyisobutenyl succinimides andsuccinates, alkyl methacrylate vinyl pyrrolidinone copolymers, alkylmethacrylate-dialkylaminoethyl methacrylate copolymers,alkylmethacrylate polyethylene glycol methacrylate copolymers,polystearamides, and polyethylenimine.

A surfactant used in preparation of the present materials can be anoil-based dispersant, which includes alkylsuccinimide, succinate esters,high molecular weight amines, and Mannich base and phosphoric acidderivatives. Some specific examples are polyisobutenylsuccinimide-polyethylenepolyamine, polyisobutenyl succinic ester,polyisobutenyl hydroxybenzyl-polyethylenepolyamine, andbis-hydroxypropyl phosphorate.

The surfactant used in preparation of the present materials can be acombination of two or more surfactants of the same or different typesselected from the group consisting of anionic, cationic, nonionic,zwitterionic, amphoteric and ampholytic surfactants. Suitable examplesof a combination of two or more surfactants of the same type include,but are not limited to, a mixture of two anionic surfactants, a mixtureof three anionic surfactants, a mixture of four anionic surfactants, amixture of two cationic surfactants, a mixture of three cationicsurfactants, a mixture of four cationic surfactants, a mixture of twononionic surfactants, a mixture of three nonionic surfactants, a mixtureof four nonionic surfactants, a mixture of two zwitterionic surfactants,a mixture of three zwitterionic surfactants, a mixture of fourzwitterionic surfactants, a mixture of two amphoteric surfactants, amixture of three amphoteric surfactants, a mixture of four amphotericsurfactants, a mixture of two ampholytic surfactants, a mixture of threeampholytic surfactants, and a mixture of four ampholytic surfactants.

In the present electrode compositions and methods for their preparation,the surfactant is added to the compositions as a weight percentage ofthe composition. In one embodiment the surfactant is present in anamount between about 0.01 wt. % and 10 wt. % of the final composition.In another embodiment the surfactant is present in an amount betweenabout 0.1 wt. % and 5 wt. % of the final composition. In yet anotherembodiment the surfactant is added in an amount between about 0.5 wt. %and 3 wt. % of the final composition.

Binders

The present electrode compositions can include one or more binderssuitable for incorporation in an electrode to allow or facilitateforming them into films and/or membranes which may be eitherfree-standing or deposited on a current collector such as copper foil;in the latter case the binders preferably provide some significantadhesion to the current collector. A membrane provides selective barrierproperties or selective transport properties, whereas a film is simply athin, continuous substrate that may or may not be porous and/orflexible. The present electrode compositions can be prepared as films ormembranes as they are designed to facilitate uptake of electrolyte.Preferably, the binder is electrochemically stable and facilitates thetransport of ions.

The binders can be electrically conductive or electricallynon-conductive. Examples include, but are not limited to, polyvinylidenefluoride (PVDF), polyacrylic acid (PAA), carboxy methyl cellulose (CMC),polyalginate, polyvinyl alcohol (PVA), polyfluorenes, perfluorosulfonicacid polymers, polyethylenimines, poly(acrylonitrile-co-acrylamide),polystyrenebutadiene rubber and poly-1,3-butadiene, and combinationsthereof.

In some embodiments of the present electrode compositions, the bindermakes up between about 0.1 wt. % and 40 wt. % of the final electrodecomposition. In some embodiments of the present electrode compositions,the binders makes up between about 0.5 wt. % and 30 wt. % of the finalelectrode composition. In yet another embodiment the binder makes upbetween about 1 wt. % and 25 wt. % of the final electrode composition.

Optional Ingredients

The present electrode compositions can also contain one or more otheroptional ingredients (in addition to the carbon nanoparticle/metal- ormetalloid-based particle mixture and surfactant and an optional binder)to provide other desired chemical and physical properties andcharacteristics. In addition to the optional components discussedseparately below, many other known types of optional ingredients such asdyes and air release agents, can also be included in the presentcompositions. In general, optional ingredients are employed in thecompositions in minor amounts sufficient to enhance the performancecharacteristics and properties of the composition. The amounts will thusvary in accordance with the intended use and properties of thecomposition. In some cases the ingredient may be included in theformulation but is essentially washed out in the fabrication processwith little or none remaining in the final composition.

Suitable optional ingredients include, but are not limited to, adhesionpromoters, antioxidants, buffering agents, corrosion inhibitors, dyes,pigments, electrolytes, fluids, friction modifiers, electrolytes,conductive aids, host materials, scale inhibitors, seal-swelling agents,solvents, stabilizers, and thickening agents.

Adhesion and Hardening Promoters

The present compositions can include one or more adhesion and hardeningpromoters. Adhesion and hardening promoters increase hardness andadhesion to substrates, such as glasses, metals, silicon wafers,amorphous silicons, and plastics. Examples of adhesion promoters includemetal complexes of Pd, Mg, W, Ni, Cr, Bi, B, Sn, In, and Pt.

Antioxidants

The present compositions can include one or more antioxidants. Examplesof antioxidants include phenolic antioxidants, aromatic amineantioxidants, sulfurized phenolic antioxidants, and organic phosphates.Examples include 2,6-di-tert-butylphenol, liquid mixtures of tertiarybutylated phenols, 2,6-di-tertbutyl-4-methylphenol, 4,4′-methylenebis(2,6-di-tert-butyl phenol),2,2′-methylenebis(4-methyl-6-tert-butylphenol), mixed methylene-bridgedpolyalkyl phenols, 4,4′-thiobis(2-methyl-6-tert-butylphenol),N,N′-di-sec-butyl-p-phenylenediamine, 4-isopropylaminodiphenylamine,phenyl-alphanaphthylamine, and phenyl-betanaphthylamine.

Buffering Agents

The present compositions can include one or more buffering agents. Thebuffering agents can be selected from known or commonly used bufferingagents. Selected buffering agents can exhibit both anti-corrosion andbuffering properties. Certain formulations such as benzoates, borates,and phosphates can provide both buffering and anticorrosion advantages.In addition, a base can be used to adjust the pH value of thecomposition. Illustrative examples of bases include commonly known andused bases, for example, inorganic bases such as KOH, NaOH, NaHCO₃,K₂CO₃, and Na₂CO₃. In addition, an acid can be used to adjust the pHvalue of the composition. Illustrative examples of acids that can beused include commonly known and used acids, for example, organic acidsincluding, but not limited to, α-hydroxy acids, such as malic acid,citric acid, lactic acid, glycolic acid, and mixtures thereof, andinorganic acids, including but not limited to mineral acids such asboric acid, hydrobromic acid, hydrochloric acid, hydrofluoric acid,nitric acid, perchloric acid, phosphoric acid, and sulfuric acid. Insome embodiments the pH will be between about 4 and about 11, preferablybetween about 5 and about 10. In other embodiments the pH will betweenabout 5 and about 7 or between about 7 and about 10. The pH valuesrecited above are for the composition during preparation.

Corrosion Inhibitors

The present compositions can include one or more corrosion inhibitorsthat can be either organic or inorganic additives. Examples of organiccorrosion inhibitors include short aliphatic dicarboxylic acids such asmaleic acid; succinic acid, and adipic acid; triazoles such asbenzotriazole and tolytriazole; thiazoles such as mercaptobenzothiazole;thiadiazoles such as 2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles,2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles,2,5-bis(hydrocarbylthio)-1,3,4-thiadiazoles, and2,5-(bis)hydrocarbyldithio)-1,3,4-thiadiazoles; sulfonates; andimidazolines. Further examples of organic corrosion inhibitors includedimer and trimer acids, such as those produced from tall oil fattyacids, oleic acid, or linoleic acid; alkenyl succinic acid and alkenylsuccinic anhydride corrosion inhibitors, such as tetrapropenylsuccinicacid, tetrapropenylsuccinic anhydride, tetradecenylsuccinic acid,tetradecenylsuccinic anhydride, hexadecenylsuccinic acid,hexadecenylsuccinic anhydride; and the half esters of alkenyl succinicacids having 8 to 24 carbon atoms in the alkenyl group with alcoholssuch as the polyglycols. Other corrosion inhibitors include etheramines; acid phosphates; amines; polyethoxylated compounds such asethoxylated amines, ethoxylated phenols, and ethoxylated alcohols;imidazolines; aminosuccinic acids or derivatives thereof. Inorganicadditives include borates, phosphates, silicates, nitrates, nitrites,and molybdates.

Copper Corrosion Inhibitors

Examples of copper corrosion inhibitors that can be included in thepresent compositions include thiazoles such as 2-mercapto benzothiazole;triazoles such as benzotriazole, tolyltriazole, octyltriazole,decyltriazole, and dodecyltriazole; and thiadiazoles such as2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles,2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles,2,5-bis(hydrocarbylthio)-1,3,4-thiadiazoles, and2,5-(bis(hydrocarbyldithio)-1,3,4-thiadiazoles.

Diluents

The present compositions can include one or more diluents. Exemplarydiluents include, mono- and di-glycidyl ethers, glycol ether, glycolether esters and glycol ether ketones, and combinations thereof.Diluents are not limited to these agents and suitable diluents can beselected based on the desired properties of the composition.

Electrolytes

Some embodiments can include electrolytes. Electrolytes are particularlysuitable when making a battery. Commercial or currently usedelectrolytes are suitable for use with the electrodes. In an embodiment,the electrolyte can further comprise conductive aids.

Fluids

Embodiments can include a fluid, which can be either hydrophilic orhydrophobic. The fluid can be a conventional fluid used in polymer andthermal transfer applications.

The fluid can be a single component or multi-component mixture. Forexample, a hydrophilic fluid can contain water, ethylene glycol, anddiethylene glycol in various proportions. The hydrophilic fluid cancontain about 0.1 to about 99.9% by volume of water, about 0.1 to about99.9% by volume of ethylene glycol, and about 0.1 to about 99.9% byvolume of diethylene glycol; and about 20 to about 80%, about 40 toabout 60%, or about 50% by volume of water or ethylene glycol.Typically, diethylene glycol constitutes a minor component of thehydrophilic fluid, in no greater than about 20%, no greater than about10%, or no greater than about 5% of the total volume.

Dipole moments, also known as electrical dipole moments, refer to ameasure of the separation of positive and negative electrical charges ina system of charges, that is, a measure of the charge system's overallpolarity. It was found that fluids having higher dipole moments resultin more rapid alignment of the nanoparticles. Therefore, in oneembodiment fluids with a dipole moment at least or greater than aboutzero (0), at least or greater than about one (1), greater than or abouttwo (2), greater than or about three (3) are used. Examples of fluidsand their corresponding dipole moments include, hexane (with a dipolemoment of zero (0)), water (with a dipole moment of 1.85), anddimethylformamide (DMF) (with a dipole moment of 3.82).

Hydrophilic Fluid

Hydrophilic fluids include hydrophilic liquid that are miscible withwater, non-limiting examples include, but are not limited to, water,aliphatic alcohols, alkylene glycols, di(alkylene) glycols, monoalkylethers of alkylene glycols or di(alkylene) glycols, and various mixturesthereof. Suitable aliphatic alcohols contain no greater than 6 carbonsand no greater than 4 hydroxyls, such as methanol, ethanol, isopropanol,and glycerol.

Suitable alkylene glycols contain no greater than 5 carbons, such asethylene glycol, propylene glycol, and 1,2-butylene glycol. In aparticular embodiment, the hydrophilic fluid comprises ethylene glycol,propylene glycol, and mixtures thereof. Ethylene glycol and propyleneglycol are excellent antifreeze agents and also markedly reduce thefreezing point of water. Suitable di(alkylene) glycols contain nogreater than 10 carbons, such as diethylene glycol, triethylene glycol,tetraethylene glycol, and dipropylene glycol.

As used herein, the term “alkylene glycol” refers to a molecule havingglycol functional moiety in its structure in general, including alkyleneglycol, alkylene glycols, di(alkylene) glycols, tri(alkylene) glycols,tetra(alkylene) glycols, and their various derivatives, such as ethersand carboxylic esters.

Hydrophobic Fluid

Hydrophobic fluids can be selected from a wide variety of well-knownorganic oils (also known as base oils), including petroleum distillates,synthetic petroleum oils, greases, gels, oil-soluble polymercomposition, vegetable oils, and combinations thereof. Petroleumdistillates, also known as mineral oils, generally include paraffins,naphthenes and aromatics.

Synthetic petroleum oils are the major class of lubricants widely usedin various industries. Some examples include alkylaryls such asdodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, anddi-(2-ethylhexyl)benzenes; polyphenyls such as biphenyls, terphenyls,and alkylated polyphenyls; fluorocarbons such aspolychlorotrifluoroethylenes and copolymers of perfluoroethylene andperfluoropropylene; polymerized olefins such as polybutylenes,polypropylenes, propylene-isobutylene copolymers, chlorinatedpolybutylenes, poly(1-octenes), and poly(1-decenes); organic phosphatessuch as triaryl or trialkyl phosphates, tricresyl phosphate, trioctylphosphate, and diethyl ester of decylphosphonic acid; and silicates suchas tetra(2-ethylhexyl)silicate, tetra(2-ethylbutyl)silicate, andhexa(2-ethylbutoxy)disiloxane. Other examples include polyol esters,polyglycols, polyphenyl ethers, polymeric tetrahydrofurans, andsilicones.

In one embodiment, the hydrophobic fluid is a diester which is formedthrough the condensation of a dicarboxylic acid, such as adipic acid,azelaic acid, fumaric acid, maleic acid, phtalic acid, sebacic acid,suberic acid, and succinic acid, with a variety of alcohols with bothstraight, cyclic, and branched chains, such as butyl alcohol, dodecylalcohol, ethylene glycol diethylene glycol monoether, 2-ethylhexylalcohol, isodecyl alcohol, hexyl alcohol, pentaerytheritol, propyleneglycol, tridecyl alcohol, and trimethylolpropane. Modified dicarboxylicacids, such as alkenyl malonic acids, alkyl succinic acids, and alkenylsuccinic acids, can also be used. Specific examples of these estersinclude dibutyl adipate, diisodecyl azelate, diisooctyl azelate, dihexylfumarate, dioctyl phthalate, didecyl phthalate,di(2-ethylhexyl)sebacate, dioctyl sebacate, dicicosyl sebacate, and the2-ethylhexyl diester oflinoleic acid dimer, the complex ester formed byreacting one mole of sebacic acid with two moles of tetraethylene glycoland two moles of 2-ethylhexanoic acid.

In another embodiment, the hydrophobic fluid is a polyalphaolefin whichis formed through oligomerization of 1-olefines containing 2 to 32carbon atoms, or mixtures of such olefins. Some common alphaolefins are1-octene, 1-decene, and 1-dodecene. Examples of polyalphaolefins includepoly-1-octene, poly-1-decene, poly-1-dodecene, mixtures thereof, andmixed olefin-derived polyolefins. Polyalphaolefins are commerciallyavailable from various sources, including DURASYN® 162, 164, 166, 168,and 174 (BP-Amoco Chemicals, Naperville, Ill.), which have viscositiesof 6, 18, 32, 45, and 460 centistokes, respectively.

In yet another embodiment, the hydrophobic fluid is a polyol ester whichis formed through the condensation of a monocarboxylic acid containing 5to 12 carbons and a polyol and a polyol ether such as neopentyl glycol,trimethylolpropane, pentaerythritol, dipentaerythritol, andtripentaerythritol. Examples of commercially available polyol esters areROYCO© 500, ROYCO® 555, and ROYCO® 808. ROYCO® 500 contains about 95% ofpentaerythritol esters of saturated straight fatty acids with 5 to 10carbons, about 2% of tricresyl phosphate, about 2% ofN-phenyl-alphanaphthylamine, and about 1% of other minor additives.ROYCO® 808 contains about 30 to 40% by weight of trimethylolpropaneesters of heptanoic, caprylic and capric acids, 20 to 40% by weight oftrimethylolpropane esters of valeric and heptanoic acids, about 30 to40% by weight of neopentyl glycol esters of fatty acids, and other minoradditives.

Generally, polyol esters have good oxidation and hydrolytic stability.The polyol ester for use herein preferably has a pour point of about−100° C. or lower to −40° C. and a viscosity of about 2 to 100centistoke at 100° C.

In yet another embodiment, the hydrophobic fluid is a polyglycol whichis an alkylene oxide polymer or copolymer. The terminal hydroxyl groupsof a polyglycol can be further modified by esterification oretherification to generate another class of known synthetic oils.Interestingly, mixtures of propylene and ethylene oxides in thepolymerization process will produce a water soluble lubricant oil.Liquid or oil type polyglycols have lower viscosities and molecularweights of about 400, whereas 3,000 molecular weight polyglycols areviscous polymers at room temperature.

In yet another embodiment, the hydrophobic fluid is a combination of twoor more selected from the group consisting of petroleum distillates,synthetic petroleum oils, greases, gels, oil-soluble polymer compositionand vegetable oils. Suitable examples include, but not limited to, amixture of two poly alphaolefins, a mixture of two polyol esters, amixture of one polyalphaolefine and one polyol ester, a mixture of threepolyalphaolefins, a mixture of two polyalphaolefins and one polyolester, a mixture of one polyalphaolefin and two polyol esters, and amixture of three polyol esters. In the embodiments, the thermal transferfluid can have has a viscosity of about 1 to about 1,000 centistokes,more preferably from about 2 to about 800 centistokes, and mostpreferably from about 5 to about 500 centistokes.

In yet another embodiment, the hydrophobic fluid is grease which is madeby combining a petroleum or synthetic lubricating fluid with athickening agent. The thickeners are generally silica gel and fatty acidsoaps of lithium, calcium, strontium, sodium, aluminum, and barium. Thegrease formulation can also include coated clays, such as bentonite andhectorite clays coated with quaternary ammonium compounds. Sometimescarbon black is added as a thickener to enhance high-temperatureproperties of petroleum and synthetic lubricant greases. The addition oforganic pigments and powders which include arylurea compoundsindanthrene, ureides, and phthalocyanines provide high temperaturestability. Sometimes, solid powders such as graphite, molybdenumdisulfide, asbestos, talc, and zinc oxide are also added to provideboundary lubrication. Formulating the foregoing synthetic lubricant oilswith thickeners provides specialty greases. The synthetic lubricant oilsinclude, without limitation, diesters, polyalphaolefins, polyol esters,polyglycols, silicone-diester, and silicone lubricants. In someembodiments nonmelting thickeners are preferred such as copperphthalocyanine, arylureas, indanthrene, and organic surfactant coatedclays.

Friction Modifiers

Suitable friction modifiers include aliphatic amines, aliphatic fattyacid amides, aliphatic carboxylic acids, aliphatic carboxylic esters,aliphatic carboxylic esteramides, aliphatic phosphonates, aliphaticphosphates, aliphatic thiophosphonates, and aliphatic thiophosphates,wherein the aliphatic group usually contains above about eight carbonatoms so as to render the compound suitably oil soluble. Also suitableare aliphatic substituted succinimides formed by reacting one or morealiphatic succinic acids or anhydrides with ammonia.

Scale Inhibitors

Certain embodiments can include scale inhibitors. Suitable scaleinhibitors include components such as phosphate esters, phosphinocarboxylate, polyacrylates, polymethacylate, styrene-maleic anhydride,sulfonates, maleic anhydride co-polymer, and acrylate-sulfonateco-polymer. The basic composition can be tailored for selectiveapplications. For example, nitrates and silicates provide aluminumprotection. Borates and nitrites can be added for ferrous metalprotection, and benzotriazole and tolytriazole can be added for copperand brass protection.

Thickening Agent

Certain embodiments can include thickening agents. Examples ofthickening agents can include, but are not limited to silica gel andfatty acid soaps of lithium, calcium, strontium, sodium, aluminum, andbarium.

Conductive Aids

Additional agents to further enhance electrical conductivity may beincluded in the formulation and may be introduced, for example, with thebinder. These conductive aids may include, but are not limited to,acetylene carbon black particles, porous carbon, graphite particles,and/or single layer or multilayer graphene particles/platelets.

Exemplary Embodiments

Exemplary ranges for components of the present electrode compositionsare shown in Table 1. All ingredients are described in weight percent ofthe total material composition.

TABLE 1 Ingredient A B C Binder  0.1-40 wt. % 0.5-30 wt. %   1-25 wt. %Metal Oxide Particles,    5-95 wt. %  10-90 wt. %  15-85 wt. % MetalParticles, Metalloid Particles, and/or Metalloid Oxide Particles CarbonNanoparticles    5-95 wt. %  10-75 wt. %  15-50 wt. % Surfactant 0.01-10wt. %  0.1-5 wt. %  0.5-3 wt. %

In one embodiment, a surfactant combined with a method of physicalagitation, such as ultrasonication, can be used to aid the homogeneousdispersion and integration of carbon nanoparticles with metals, metaloxides, metalloids or metalloid oxides. After the surfactant has beenadsorbed on the nanoparticles' surface, ultrasonication can debundle thenanoparticles by steric or electrostatic repulsions.

It has been discovered that the ratio of the nanoparticles to thesurfactant that it used can be important in influencing the propertiesof the material. As such, the nanoparticles and surfactant can be in aratio of from about 100:1 to about 1:20, preferably from about 1:3 toabout 1:15, more preferably from about 1:5 to about 1:12 by weight. Insome embodiments the ratio of nanoparticles to surfactant is betweenabout 1:7 and about 1:10 by weight. The ratios referred to above are forthe mixture as it is being mixed. The ranges for the ratios recited areinclusive of the numbers defining the range and include each integer andfractions within the defined range of ratios.

In one embodiment, the present electrode compositions exhibit improvedelectrical properties relative to carbon nanoparticles. For example, theactive materials in the electrode compositions (metal particles, metaloxide particles, metalloid particles, and/or metalloid oxide particlesin combination with carbon nanoparticle materials) can have a specificcapacity (often expressed as milliamp-hours per weight such as per gram,abbreviated as mAh/g) improvement over the carbon nanoparticles and overgraphite of at least 5%. The capacitance will be limited by thecapacitance of the metal, metal oxide, metalloid or metalloid oxide;however, capacitance can be affected by the selection of particularmetals and/or metal oxides. In one embodiment, the present electrodecompositions have a specific capacity of at least 450 mAh/g, preferablyat least 500 mAh/g, and more preferably at least 600 mAh/g of activematerial when cycled at a charge/discharge rate of about 0.1 C (10 hourcharge and 10 hour discharge rate).

In one embodiment, the present electrode compositions have improvedelectrical properties relative to metal oxide nanoparticles, metalloidnanoparticles or metal nanoparticles. For further example, certainembodiments are expected to have improved electrical conductivityrelative to metal oxide nanoparticles and metalloid nanoparticles ofabout at least 1 order of magnitude.

The present compositions can be prepared in many diverse forms, withmany different properties, and for many intended applications. Forexample, some of the present compositions can form electrodes withimproved charge/discharge capacity, conductivity, improved number ofcycle lifetimes, rechargeability, and reversibility.

In some embodiments the compositions can form an anode. Preferred metalparticles, metal oxide particles, metalloid particles, and/or metalloidoxide particles for anodes include Al₂O₃, CuO, MgO, SiO₂, GeO₂, B₂O₃,TeO₂, V₂O₅, BiO₂, Sb₂O₅, TiO₂, ZnO, FeO, Fe₂O₃, Fe₃O4, CrO₃, NiO, Ni₂O₃,CoO, CO₂O₃, and CO₃O₄.

In some embodiments the compositions can form a cathode. Preferred metalparticles, metal oxide particles, metalloid particles, and/or metalloidoxide particles for cathodes include LiFePO₄, LiCoO₂, LiMn₂O₄, andLiNi_(1/3)Mn_(1/3)Co_(1/3)O₂, LiNiO₂, LiNi_(0.8)Co_(0.15)Al_(0.05)O₂,LiMn_(3/2)Ni_(1/2)O₄, LiFe_(1/2)Mn_(1/2)PO₄, Li₄Ti₅O₁₂.

In some embodiments of the present methods for making the electrodecompositions, particular dispersion techniques are employed to providehomogenously mixed carbon nanoparticles (for example, graphene,nanotubes, carbon nanofiber) and metal oxides and/or metal particles. Ithas been discovered that using a surfactant can cause metal oxidesand/or metal particles to attach to carbon nanoparticles more uniformly.It is believed that metal oxide particles, metal and/or metalloidparticles collect on the surface of carbon nanoparticles byelectrostatic attraction (for example, metal oxides have positive zetapotential charge at proper pH and carbon nanotubes have negative chargedue to surfactant which may attach to the carbon surface via thehydrophobic head) and form a well dispersed deposition of metalparticles, metal oxide particles, metalloid particles, and/or metalloidoxide particles integrated to the carbon nanomaterials.

FIGS. 1-6 provide illustrative images showing example metal oxideparticles, metal and/or metalloid particles collected and attached to avariety of example nanofibers, nanotubes, and/or other nanoparticles.

FIG. 1 is a scanning electron microscope (SEM) image (magnification29,380) of iron oxide (Fe₂O₃) nanoparticles substantially uniformlyattached to carbon nanofibers (surfactant: sodium dodecylbenzenesulfonate). It can be seen that the Fe₂O₃ nanoparticles (black dots) arespatially distributed on the surface of the nanofibers in asubstantially non-aggregated arrangement with few or no instances ofFe₂O₃ nanoparticles stacked on top of each other.

FIG. 2 is an SEM image (magnification 16,810) of silicon (Si)nanoparticles attached to carbon nanofibers (surfactant:cetyltrimethylammonium bromide). It can be seen that the Sinanoparticles (black dots) are spatially distributed on the surface ofthe nanofibers in a substantially non-aggregated arrangement with few orno instances of Si nanoparticles stacked on top of each other.

FIG. 3 is an SEM image (magnification 62,270) of silicon (Si)nanoparticles attached to single wall carbon nanotubes (C-SWNT)(surfactant: cetyltrimethylammonium bromide). It can be seen that the Sinanoparticles (black dots) are spatially distributed on the surface ofthe C-SWNTs in a substantially non-aggregated arrangement with few or noinstances of Si nanoparticles stacked on top of each other.

FIG. 4 is an SEM image (magnification 35,120) of silicon (Si)nanoparticles attached to single wall carbon nanotubes (C-SWNT)(surfactant: benzethonium chloride). It can be seen that the Sinanoparticles (black dots) are spatially distributed on the surface ofthe C-SWNTs in a substantially non-aggregated arrangement with few or noinstances of Si nanoparticles stacked on top of each other.

FIG. 5 is a transmission electron microscope (TEM) image (the scale baris 200 nm) of iron oxide (Fe₂O₃) nanoparticles attached to graphene(surfactant: sodium dodecylbenzenesulfonate). Although the transmissionimages include many multilayer regions (especially the lower section)which obscures analysis in these regions, the Fe₂O₃ nanoparticles(hexagonal shapes) appear spatially distributed on the surface of thegraphene in a substantially non-aggregated arrangement.

FIG. 6 is a transmission electron microscope (TEM) image (the scale baris 500 nm) of silicon (Si) nanoparticles substantially uniformlyattached to graphene (surfactant: benzethonium chloride). Although thetransmission images include some multilayer regions which obscuresanalysis in these regions, the Si nanoparticles (circular shapes) appearspatially distributed on the surface of the graphene in a substantiallynon-aggregated arrangement.

Electrochemical Device

FIG. 7 shows in cross-sectional a thin film lithium-ion battery 10.Battery 710 includes an anode 712, a cathode 714 and an electrolyte 716interposed between anode 712 and cathode 714. Anode 712 and/or cathode714 have an electrode composition as described herein. An anode currentcollector 718 is in electrical contact with anode 712. Similarly, acathode current collector 720 is in electrical contact with cathode 714.Gas diffusion layer or substrate 722 is located adjacent cathode currentcollector 720. In certain examples, a separator (such as a polymerseparator, nonwoven fiber separator, and/or other membrane separator)(not shown) is provided between anode 712 and cathode 714 to preventelectrical short circuits between anode 712 and cathode 714 while stillallowing transport of charged ions for current flow in battery 710.Separator is chemically and electrochemically stable with respect toelectrolyte 716 while allowing ions to move between anode 712 andcathode 714. Protective layer 726 joins with substrate 722 to encase theremaining components of battery 710.

Using one or more of the example electrode compositions disclosed hereinto form anode 712 and/or cathode 714 provides higher capacity and higherperformance in energy storage systems when compared to prior electrodecompositions. Through non-aggregated integration of carbon nanoparticles(for example, graphene, nanotubes, carbon nanofiber) with metal oxideparticles, metal particles, metalloid particles, and/or metalloid oxideparticles, anode 712 and/or cathode 714 can be formed with desirableproperties including, but not limited to, improved charge capacity,conductivity, improved number of cycle lifetimes, improvedrechargeability, and/or reversibility, for example. Ion absorbingparticles are integrated with magnetically aligned carbon nanoparticlesto provide improved electrochemical cell functionality and operatingperformance while reducing heat generation and malfunction. Suchcombination results in improved physical properties, including, but notlimited to, electrical conductivity, thermal conductivity, increasedtensile modulus (stiffness), flexural modulus, tensile strength,flexural strength, elasticity, and toughness.

Battery 710 can be used to power a variety of devices including laptopcomputers, tablet computers, smartphones, hybrid and/or electric cars,and/or other electronic devices, for example. Battery 710 can bedirectly connected as a power source and/or included as part of abattery assembly, for example.

Methods of Preparing Electrodes

Electrodes can be prepared using the composite materials describedherein. Various methods can be used to solidify and form the materialinto a desired shape. In most cases, a binder is used as a matrix forthe metal/carbon nanoparticle or metal oxide/carbon nanoparticlematerial.

As described above, a surfactant can be used to facilitate thehomogeneous dispersion of carbon nanoparticles and metal oxides and/ormetal particles. Dispersion can also be aided by physical agitation, asdescribed above. Following the dispersion of carbon nanoparticles andmetal oxides and/or metal particles, excess surfactant is removed. Thiscan be done, for example, through filtration or centrifugation. Anysuitable liquid can be used to wash off excess surfactant. For examplein some cases water, ethanol, or isopropyl alcohol can be used. Afterthe excess surfactant is removed, some residual surfactant may remain.Preferably, only the surfactant that serves to attach the metal, metaloxide, metalloid or metalloid oxide particles to the carbonnanoparticles remains. A binder can then be added to the dispersedcarbon nanoparticles and metal, metal oxide, metalloid or metalloidoxide to form an electrode.

FIG. 9 is a graph showing the change in charge capacity over multiplelife (charge/discharge) cycles for an electrode comprising about 75 wt.% Fe₂O₃ nanoparticles attached to about 25 wt. % graphene Sodiumdodecylbenzenesulfonate was the surfactant employed in the materialpreparation. The binder employed in preparing this dispersion waspolyacrylic acid (PAA). This formulation demonstrates substantiallybetter charge capacity, in the region of 700 mAh/g, when compared withelectrodes made of graphite, which typically have a specific capacityaround 350 mAh/g.

The significance of including a suitable surfactant is illustrated bycomparing FIG. 9 with FIG. 8 , which shows a formulation comprising 75wt. % Fe₂O₃ and 25 wt. % graphene, but where no surfactant was includedin the formulation. In this case, substantial capacity fade is evidentin the first 3 or 4 (charge/discharge) cycles and the electrode capacityis much lower than for the electrode prepared with surfactant.

FIG. 10 is a graph showing the change in charge capacity over multiplelife (charge/discharge) cycles for an electrode comprising about 50 wt.% silicon nanoparticles attached to about 50% wt. % graphenenanoparticles. Benzyldodecyldimethylammonium bromide surfactant wasemployed in preparing the electrode. The binder employed in preparingthis dispersion was polyacrylic acid (PAA). Again, this formulationdemonstrates substantially better charge capacity, in the region of 1200mAh/g, when compared with electrodes made of graphite, which typicallyhave a capacity of about 350 mAh/g.

Physical Agitation

A uniform and stable dispersion of nanoparticles plays an important rolein the formation of homogeneous and integrated carbon nanoparticle/metaloxide, or carbon nanoparticle/metal nanoparticle compositions. When thecarbon nanoparticles are aggregated in a composition, the poordispersion can cause non-uniform load and weaken the conductivity andcapacitance and can adversely affect other properties of the material.

The compositions can be prepared by conventional means of dispersing amixture of the appropriate carbon nanoparticles, metal oxides and/ormetal nanoparticles, surfactant(s), and/or other optional additives,including binder(s). For example, a common approach is using a physicalmethod to form a stable suspension of nanoparticles in a fluid. Avariety of physical mixing methods are suitable, including aconventional mortar and pestle mixing (for dry materials), high shearmixing, such as with a high speed mixer, a rotor-stator mixer, milling,homogenizers, microfluidizers, high impact mixing, stirring (bothmanually and/or with the use of a stir bar), centrifugation, andultrasonication methods. The various physical mixing methods can beperformed at room temperature, cooled temperatures, and/or heatedtemperatures.

One method of physical agitation is stirring, in particular with the useof a stir bar. Another method of physical agitation is ultrasonication.Ultrasonication is one of the less destructive methods to the structuresof nanoparticles, in particular carbon nanotubes, if used under suitableoperating conditions. Ultrasonication can be done either in thebath-type ultrasonicator, or using a tip-type ultrasonicator. Typically,tip-type ultrasonication is for applications which require higher energyoutput. Ultrasonication can be performed, for example, at anintermediate intensity for up to 60 minutes. Additionally, the mixturecan be ultrasonicated intermittently to avoid overheating, or a chillercan be used, especially when a flow-through cell is employed. It is wellknown that overheating can cause covalent bond breakage in carbonnanotubes, which causes the nanotubes to lose some of its beneficialphysical properties. As such, in the case of batch processing, thecarbon nanoparticle-containing mixture is generally energized for apredetermined period of time with a break in between. Each energizingperiod is no more than about 30 minutes, no more than about 15 minutes,no more than 10 minutes, no more than 5 minutes, no more than 2 minutes,no more than 1 minute, or no more than 30 seconds. The break betweenenergizing periods provides an opportunity for the energized carbonnanoparticles to dissipate the energy. The break is typically no lessthan about 1 minute, no less than about 2 minutes, no less than about 5minutes, or between about 5 to about 10 minutes.

The raw material mixture can be pulverized by a suitable dry or wetgrinding method. One grinding method includes pulverizing the rawmaterial mixture in a liquid host material to obtain a concentrate orpaste, and the pulverized product can then be dispersed further in aliquid host material with the aid of surfactants as described above.However, pulverization or milling often reduces the carbon nanoparticleaverage aspect ratio which can have a detrimental effect on theproperties of the final material.

Individual components (for example, carbon nanoparticles, metals, metaloxides) can be separately blended into a liquid host material, or can beblended therein in various sub-combinations, if desired. Ordinarily, theparticular sequence of such blending steps is not critical. Moreover,such components can be blended in the form of separate solutions in adiluent. However, to simplify the blending operations, reduce thelikelihood of blending errors, and take advantage of the compatibilityand solubility characteristics afforded by the overall concentrate, onecan blend the components used in the form of an additive concentrate.

In one embodiment, the method of physical agitation comprises, consistsof, or consists essentially of stirring and/or ultrasonication. Inanother embodiment, the dispersing steps can comprise, consist of, orconsist essentially of ultrasonication in a batch process or in acontinuous flow-through ultrasonication process. In one embodiment, theduration of the ultrasonication is between about 5 seconds and about 50minutes, preferably between about 5 minutes and about 40 minutes, morepreferably between about 10 minutes and about 30 minutes, and even morepreferably between about 15 minutes and about 20 minutes. The intensityof the ultrasonication is between about 5% and about 80% amplification,preferably between about 10% and about 70% amplification, morepreferably between about 20% and about 60% amplification, and mostpreferably between about 30% and about 50% amplification. The amount oftime and intensity of the physical agitation will be determined by themethod and scale of production.

FIG. 11 is a flow diagram illustrating an example method 1100 of formingan electrode, such as an anode or cathode for an electrochemical batterycell. Example method 1100 may include one or more operations, functions,or actions as illustrated by one or more of blocks 1110-1180. Althoughthe blocks are illustrated in sequential order, these blocks may also beperformed in parallel, and/or in a different order than those describedherein. Also, the various blocks may be combined into fewer blocks,divided into additional blocks, and/or removed based upon the desiredimplementation. In addition, for the example method 1100 and otherprocesses and methods disclosed herein, the flowchart showsfunctionality and operation of one possible implementation of presentembodiments.

At block 1110, a first suspension is prepared using carbonnanoparticles. For example, a first suspension of carbon nanoparticles(for example, graphene, carbon nanotubes, or carbon nanofibers) isprepared in a fluid (for example, deionized water).

In certain examples, a surfactant is first dispersed (for example, usingultrasonication or centrifugation) in a fluid (for example, deionizedwater) to form a clear solution in which the carbon nanoparticle is thenadded to prepare the first suspension. In certain examples, thesuspension can be mixed by stirring the solution (for example, using amagnetic bar).

At block 1120, material in the first suspension is dispersed with asurfactant. Physical agitation, such as ultrasonication orcentrifugation, can be used to disperse the carbon nanoparticles in thefirst suspension. In certain examples, stirring of the suspension cancontinue following dispersion by ultrasonication.

At block 1130, a second suspension is prepared using one or more ofmetal oxide particles, metal particles, metalloid particles, and/ormetalloid oxide particles. For example, a second suspension of metaloxide particles, metal particles, metalloid particles, and/or metalloidoxide particles (for example, a suspension of iron oxide or siliconparticles) is prepared in a fluid (for example, deionized water).

In certain examples, rather than forming a separate second suspension,the second suspension is formed from the first suspension by adding theone or more of metal oxide particles, metal particles, metalloidparticles, and/or metalloid oxide particles to the first suspension. Inother examples, the second suspension is formed separately from thefirst suspension, mixed, and added to the first suspension.

At block 1140, material in the second suspension is dispersed andcombined with the first suspension. For example, ultrasonication orcentrifugation can be used to disperse the nanoparticles in the secondsuspension.

At block 1150, the combined first and second suspensions are filtered(for example, using a funnel or filter and vacuum) and dried into aresidue. Residue can then be scraped off of the filter and ground (forexample, using a mortar and pestle or milling techniques).

At block 1160, a binder is added to form an electrode composition. Incertain embodiments, the combined residue of the first and secondsuspensions can be redispersed in a fluid (for example, deionized water)prior to adding the binder. In certain embodiments, a binder can beadded to the combined suspension followed by further dispersion (forexample, using ultrasonication or centrifugation) of the combinedsuspension to form an electrode composition. In certain embodiments, aslurry is prepared using the ground residue of carbon nanoparticle andat least one of metal oxide particles, metal particles, metalloidparticles, and/or metalloid oxide particles with a fluid (for example,deionized water), which may contain binder.

In certain examples, one or more optional ingredients including, but notlimited to, adhesion and hardening promoters, antioxidants, bufferingagents, corrosion inhibitors, diluents, electrolytes, fluids (forexample, hydrophilic fluid or hydrophobic fluid), friction modifiers,scale inhibitors, thickening agent, and/or conductive aids can be addedto the first suspension, second suspension and/or resulting mixture.

At block 1170, the electrode composition is transferred to a currentcollector to form one or more electrodes. For example, the electrodecomposition is sprayed, applied by doctor blade and/or otherwise appliedin a layer on a copper foil and may include further or subsequentcompression of the electrode composition. In alternate embodiments, theelectrode composition is formed as a free-standing film or membrane.

At block 1180, electrode composition is dried. For example, the currentcollector is heated to dry the material remaining on the currentcollector to form dried electrode material. In an alternate embodiment,where the electrode is a free-standing film or membrane, the driedelectrode composition is separated and formed into one or moreelectrodes.

In certain examples, a resulting electrode has a specific capacity of atleast 450 mAh/g, preferably of at least 600 mAh/g, of active materialwhen cycled at a charge/discharge rate of about 0.1 C. Electrodes usedin cell assembly to form one or more batteries (for example, as anodeand/or cathode for one or more batteries). For example, one or morelithium-ion batteries (for example, a coin cell battery, automotivebattery, computer battery, or cell phone battery) can be formed usingthe dried electrode composition.

EXAMPLES Comparative Example 1

As a comparative example, a Fe₂O₃/graphene anode was prepared withoutusing a surfactant in the material preparation process. A graphenesuspension was prepared by adding 0.04 g Fe₂O₃ nanoparticle into 20 mldeionized water. The graphene suspension was mixed with a magneticstirring bar at 800 revolutions per minute (rpm) for 2 hours, andfurther dispersed by ultrasonication using a Misonix Sonicator (S-4000)for 15 minutes at 30 W power output. The graphene suspension was thentransferred back on the magnetic plate and stirring was continued. AFe₂O₃ nanoparticle suspension was prepared by mixing 0.12 g Fe₂O₃nanoparticle into 60 ml deionized water and stirred by a mechanicalmethod for 2 hours. The suspension was then subject to ultrasonicationusing a Misonix Sonicator (S-4000) for 5 minutes at 30 W power output.The as-prepared 20 ml graphene suspension was then transferred into theFe₂O₃ nanoparticle suspension slowly. The mixture was sonicated for atotal of 30 min with a 5 min interval of rest after 15 minutes ofultrasonication. 0.8 grams of polyacrylic acid (PAA) binder in 5 wt. %water solution was last added into the suspension, and the final mixturewas further sonicated for another 15 min. The obtained mixture wassprayed onto a heated copper foil (current collector) at 140° C. using aPaasche Air Brush Kit. Compressed air was used as carrying gas and thepressure was controlled at 18 psi. The distance between the nozzle andthe current collector was kept in the range of 10-20 cm. The obtainedelectrodes were transferred in a vacuum oven and heated at 80° C. for 16hours. The formed electrode composition was punched into 2.5 cm diameterpellets, and then transferred to an argon gas filled glove box for cellassembly. The pellet was assembled into CR2032 type of coin cell batterywith lithium foil as counter electrode. 1M LiPF₆ in a mixture ofethylene carbonate/diethylene carbonate at 1:1 volume ratio was used aselectrolyte solution, Celgard®3501 micro-porous membrane was used asseparator. The cell was cycled by discharge-charge between 0.05 and 3V(vs. Li/Li+) using an Arbin™ battery test station at a rate of 0.1 C.The discharge capacity over multiple cycles for this anode material, inwhich no surfactant was used in the material preparation is shown inFIG. 8 , from which it can be seen that there is rapid fade of capacitywith cycling.

Specific Example 2

A Fe₂O₃/graphene anode was prepared using surfactant in the materialpreparation process as follows. Ultrasonication was performed with aBranson Model 450 Digital Sonifier with a ½″ disrupter horn. Initially,1 g surfactant (sodium dodecylbenzenesulfonate) was first dispersed indeionized water by sonicating for 15 minutes with the amplitude of 20%until a clear solution was achieved. Then, 0.05 g graphene was added tothe solution and sonicated for an additional 15 minutes with the sameamplitude, repeated twice. Finally, 1.5 g Fe₂O₃ nanoparticles were addedto the mixture and sonicated for 30 minutes. The prepared fluids wereadded to the funnel connected with vacuum filtration. When the liquidlevel approached the bottom of the funnel, more deionized water isadded. 150 ml water was used. The filter was taken out of the funnel andleft in the vacuum oven (80° C., 20 inches of mercury) for 12 h. Thesample was then scraped off the filter and ground by marble pestle andmortar. The electrode comprising metal oxide and graphene were preparedusing a slurry spray technique. 0.05 grams of electrode compositionconsisting of 75 wt. % Fe₂O₃ nanoparticles, 25 wt. % graphene, and wasfurther mixed with 0.25 grams of PAA in 5 wt. % water solution. Theratio of the active material (Fe₂O₃ nanoparticles/graphene compositematerial) to PAA was 8:2. 10 ml deionized water was added into theslurry. The slurry was mixed by mechanical stirring method for 4 hours.The obtained slurry was sprayed onto a heated copper foil (currentcollector) at 140° C. using a Paasche Air Brush Kit. Compressed air wasused as carrying gas and the pressure was controlled at 18 psi. Thedistance between the nozzle and the current collector was kept in therange of 10-20 cm. The obtained electrodes were transferred to a vacuumoven and heated at 80° C. for 16 hours. The formed electrode compositionwas then punched into 2.5 cm diameter pellets, then transferred to anargon gas filled glove box for cell assembly. The pellet was assembledinto CR2032 type of coin cell battery with lithium foil as counterelectrode. 1M lithium hexafluorophosphate (LiPF₆) in a mixture ofethylene carbonate/diethylene carbonate at 1:1 volume ratio was used aselectrolyte solution, Celgard® 3501 micro-porous membrane was used asseparator. The cell was cycled by discharge-charge between 0.05 and 3V(vs. Li/Li+) using an Arbin™ battery test station at a rate of 0.1 C.The discharge capacity over 94 cycles for this anode material, in whichsodium dodecylbenzenesulfonate surfactant was used in the materialpreparation, is shown in FIG. 9 , from which it can be seen that theanode capacity is in the region of 700 mAh/g and shows no indication ofcapacity fade. Stable cycling in the region of 750 mAh/g continues forthis sample.

Specific Example 3

A silicon/C-SWNT anode was prepared using surfactant in the materialpreparation process as follows. Sonication was performed with a BransonModel 450 Digital Sonifier with a ½″ disrupter horn. Initially, 0.5 gsurfactant (benzyldodecyldimethylammonium bromide (BddaBr)) was firstdispersed in deionized water by using sonication for 15 minutes with theamplitude of 20% until a clear solution was achieved. Then, 0.05 gsingle wall carbon nanotube (SWNT) was added to the solution andsonicated for an additional 15 minutes with the same amplitude, repeatedfor two times. Finally, 0.05 g Si nanoparticles (size 50-70 nm) wereadded to the mixture and sonicated for 10 minutes, with the amplitude of15%. The prepared fluids were added to the funnel connected with vacuumfiltration. When the liquid level approached the bottom of the funnel,more deionized water was added. 200 ml of water was used. The filter wastaken out of the funnel and left in the vacuum oven (80° C., 20 inchesof mercury) for 12 h. The sample was then scraped off the filter andground by marble pestle and mortar. The electrode comprising silicon(Si) and carbon nanotube (CNT) were prepared using a slurry spraytechnique. 0.05 grams of electrode composition consisting of 50 wt. % Sinanoparticles, 50 wt. % CNTs, and was further mixed with 0.25 grams ofPAA binder in 5 wt. % water solution. The ratio of the active material(Si nanoparticles-CNT composite material) to PAA was 8:2. 10 mldeionized water was added into the slurry. The slurry was mixed bymechanical stirring method for 4 hours. The obtained slurry was sprayedonto a heated copper foil (current collector) at 140° C. using a PaascheAir Brush Kit. Compressed air was used as carrying gas and the pressurewas controlled at 18 psi. The distance between the nozzle and thecurrent collector was kept in the range of 10-20 cm. The obtainedelectrodes were transferred in vacuum oven and heated at 80° C. for 16hours. The formed electrode composition was then punched into 2.5 cmdiameter pellets, then transferred to an argon gas filled glove box forcell assembly. The pellet was assembled into CR2032 type of coin cellbattery with Lithium foil as counter electrode. 1M LiPF₆ in a mixture ofethylene carbonate/diethylene carbonate at 1:1 volume ratio was used aselectrolyte solution, Celgard®3501 micro-porous membrane was used asseparator. The cell was cycled by discharge-charge between 0.05 and 0.7V (vs. Li/Li+) using an Arbin™ battery test station at a rate of 0.1 C.The discharge capacity over 23 cycles for this anode material, in whichbenzyldodecyldimethylammonium bromide surfactant was used in thematerial preparation, is shown in FIG. 10 , from which it can be seenthat the anode capacity is in the region or 1200 mAh/g to 1300 mAh/g andshows no indication of capacity fade. Stable cycling in the region of1250 mAh/g continues for this sample.

While particular elements, embodiments and applications of the presentinvention have been shown and described, it will be understood, that theinvention is not limited thereto since modifications can be made bythose skilled in the art without departing from the scope of the presentdisclosure, particularly in light of the foregoing teachings.

What is claimed is:
 1. An electrode comprising: (a) a graphite; (b) atleast one of silicon or silicon dioxide; (c) a surfactant for attachingsaid graphite to said at least one of silicon or silicon dioxide byelectrostatic attraction at a pH of between about 4 and 11 to form anelectrode composition; wherein the surfactant is an anionic, cationic,zwitterionic, amphoteric, or ampholytic surfactant; (d) a binder forforming said electrode composition into a film or membrane; wherein saidelectrode has a specific capacity of at least 450 mAh/g of activematerial when cycled at a charge/discharge rate of about 0.1 C.
 2. Theelectrode of claim 1, wherein said surfactant comprises at least one ofsodium dodecylbenzenesulfonate (SDBS) and benzyldodecyldimethylammoniumbromide (BddaBr).
 3. The electrode of claim 1, wherein said electrode isan anode.
 4. The electrode of claim 1, wherein said electrode is acathode.
 5. The electrode of claim 3, further comprising at least one ofthe following oxides: Al₂O₃, CuO, MgO, GeO₂, B₂O₃, TeO₂, V₂O₅, BiO₂,Sb₂O₅, TiO₂, ZnO, FeO, Fe₂O₃, Fe₃O₄, CrO₃, NiO, Ni₂O₃, CoO, Co₂O₃, andCo₃O₄; and wherein said electrode has a specific capacity of at least600 mAh/g of active material when cycled at a charge/discharge rate ofabout 0.1 C.
 6. The electrode of claim 5, wherein said oxide is Fe₂O₃.7. The electrode of claim 4, further comprising at least one of thefollowing oxides: LiFePO₄, LiCoO₂, LiMn₂O₄,LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂, LiNiO₂, LiNi_(0.8)Co_(0.15)Al_(0.05)O₂,LiMn_(3/2)Ni_(1/2)O₄, LiFe_(1/2)Mn_(1/2)PO₄, and Li₄Ti₅O₁₂.
 8. Theelectrode of claim 1, further comprising at least one of the following:lanthanum, cerium, praseodymium, neodymium, promethium, samarium,europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium,ytterbium, lutetium, cobalt, vanadium, manganese, niobium, iron, nickel,copper, boron, titanium, germanium, tellurium, zirconium, tin, scandium,yttrium, oxides of the aforementioned metals and metalloids, and alloysof the aforementioned metals and metalloids.
 9. The electrode of claim1, wherein said at least one of silicon and silicon dioxide is in theform of nanoparticles.
 10. The electrode of claim 1, wherein saidsurfactant has a net negative charge and a pH value greater than thepHpzc of said at least one of silicon and silicon dioxide.
 11. Theelectrode of claim 10, wherein said surfactant is selected from thegroup consisting of sodium dodecylbenzenesulfonate (SDBS) and sodiumdodecyl sulfate (SDS).
 12. The electrode of claim 1, wherein saidsurfactant has a net positive charge and a pH value less than the pHpzcof said at least one of silicon and silicon dioxide.
 13. The electrodeof claim 12, wherein said surfactant is selected from the groupconsisting of cetyltrimethylammonium bromide (CTAB),benzyldodecyldimethylammonium bromide (BddaBr),benzyldimethylhexadecylammonium chloride (BdhaCl),didodecyldimethylammonium bromide (DDAB), amprolium hydrochloride (AH),and benzethonium chloride (BC).
 14. The electrode of claim 1, whereinsaid graphite and said at least one of silicon and silicon dioxide arenon-aggregating.
 15. The electrode of claim 14, wherein said graphiteand said at least one of silicon and silicon dioxide are dispersedhomogeneously.
 16. The electrode of claim 1, wherein said bindercomprises at least one of polyvinylidene fluoride (PVDF), polyacrylicacid (PAA), carboxy methyl cellulose (CMC), polyalginate, polyvinylalcohol (PVA), polyfluorenes, polyurethane, perfluorosulfonic acidpolymers, polyethylenimines, poly(1,3-butadiene),poly(acrylonitrile-co-acrylamide), polystyrenebutadiene rubber, andpoly(9,9-dioctylfluorene-co-9-fluorenone-co-methybenzoic ester) (PFM).17. The electrode of claim 16, wherein said binder comprises polyacrylicacid (PAA).
 18. The electrode of claim 1 further comprising one or morecarbon nanoparticles.
 19. The electrode of claim 18, wherein said one ormore carbon nanoparticles are selected from the group consisting ofgraphene nanoparticles, carbon nanotubes, and carbon fibers.
 20. Theelectrode of claim 1 further comprising one or more additional metalloidparticles and/or metalloid oxide particles.
 21. The electrode of claim 1further comprising at least one of metal particles and metal oxideparticles.